0:10Skip to 0 minutes and 10 secondsTo the question, "What is a mind?", I'm answering that it's the subjective aspect of the body. It's the being of a body. And that leads to the question, what about other bodies? And there, we have the problem of other minds. If you have to be the body to know whether it has a mind or not, what about others? You can't ever be another body. Philosophers think this problem of other minds is a huge problem. In fact, they think it's insoluble. But how is it then that us regular folk in everyday life, we seem to have no trouble relating to other bodies on the assumption that they have minds?

0:46Skip to 0 minutes and 46 secondsWell, the way we do it, it pivots around the word I've just used, "on the assumption." We don't require absolute knowledge. We don't want absolute truth in life. I mean, we'd want it. It's nice. But we know we can't have it. We relegate absolute truth to things like religion, and in our actual daily lives we get by on assumptions. In this way we function, in fact, a lot like scientists do. Science is a sort of systematic common sense. In science, we also don't have absolute truths. We can't know things for sure. But we make the best guess we can based on the available evidence, and that enables us to get ahead.

1:28Skip to 1 minute and 28 secondsWe use those theories, those hypotheses about how the world works, to get on with the job. And if we come up with better theories, then they work better, and then we use those. We use the best ones that we've got for the moment, provisional truth. So what regular folk do is-- let me unpack it for you and show how it's actually a sort of science. Everyday life works in much the same way. The technical term for how we come to know other minds in everyday life is empathy. Empathy means feeling your way into something. To empathise with something is to do that. How do we feel our way into another body? I think we do it something like this.

2:18Skip to 2 minutes and 18 secondsWhen you wake up in the morning, you feel yourself to be, in my case, Mark Solms. Then you stagger out of bed and you see yourself in the mirror, and you realise that that object over there, that body, is me. I have felt my way into that body. I have, as it were, empathised with my body. I notice whenever I intend certain things to happen to my body externally, I see that they happen. When I feel certain things, I notice my facial expression tallies in a certain way with what I'm feeling, and so on. I see the correlations between my mental states-- that is to say, my subjective states-- and my bodily states-- that is to say, my objective actions.

3:07Skip to 3 minutes and 7 secondsAnd in this way, I infer that anyone else that behaves like that probably has mental states behind them in the same way as my body does. I say probably. Remember, I've already confessed that it's not absolute knowledge, but it works. I assume if you smile that you're feeling like I do when I smile. I infer that if you withdraw your hand from the prick of a pin, you're doing that because you're feeling pain like I do when I'm pricked with a pin. It seems like a reasonable guess that you're feeling what I do. That's how we do it in science. We make a hypothesis.

3:51Skip to 3 minutes and 51 secondsWe then say, if the that hypothesis is true then if I do the following thing, which we call an experiment, I predict that the following outcome will occur. If that outcome does occur, I provisionally hold my hypothesis to be correct. It's very important that it must be possible for that outcome not to occur, in which case I've falsified it and then I have to change my hypothesis. That's what we do in science. And I see no reason why we can't do that with the thing that I'm talking to you about, the subjective mind. Please note it starts with the subjective mind. You start with my experience is like this. That tallies with a body that looks like that.

4:31Skip to 4 minutes and 31 secondsTherefore, when I see other bodies that look like that, I infer that they have experiences like this. The subject in this way is included in science. I want you to notice two things about this before I proceed. The one is notice the importance of the body. Philosophers call this the mind-body problem. It's another problem in philosophy. How do you know exactly how the mind and body relate? In this rough and ready scientific way that I'm describing which, as I say, tallies with everyday experience, I work on the hypothesis that that thing that I see from the outside, my body, and this thing that I experience on the inside, me, I infer they're the same thing.

5:15Skip to 5 minutes and 15 secondsThere probably aren't two Mark Solms, one his body and the other his mind. I infer that these are just two different ways of observing me-- the one subjectively, my mind, the other objectively, my body. This so-called problem, the mind-body problem, actually becomes thereby a great opportunity for us in science, because now I can do science on my body and correlate it with the mental states that arise from it. And in this way, mental states are included in science in a very simple, ordinary way. The other thing I want you to notice about what I'm saying is that the body is a really important part of mental science. And that brings us back to ELIZA.

5:57Skip to 5 minutes and 57 secondsRemember, Turing said we have to exclude the visual information. We're not allowed to look at ELIZA when deciding whether she has a mind or not. But obviously, if you were to look at ELIZA and see she has a body like yours, you would interpret very differently what she says than if you were to look at ELIZA and find that she's a little computer keyboard in reality-- a computer, whatever those things are called inside computers, a programme. The visual information, the information as to what kind of body you're dealing with, I think is highly relevant. And I hope to be able to unpack that more as we proceed.

6:37Skip to 6 minutes and 37 secondsSo let's go back to being able to do science, to being able to do experiments in the way that I'm describing. To have a proper science of mind, you have to do the right sort of experiments. Remember, what we're trying to do is to decide what other bodies have minds and which ones don't. I've already said that if you do an experiment which requires the other thing to talk to you, as in the Turing test, that might be the wrong experiment.

7:03Skip to 7 minutes and 3 secondsIf, for example, I was to ask a dog, "Do you have a mind?"-- and my prediction would be that an animal that has a mind, a body that has a mind would reply "yes" to that question-- and if I say that to a dog and it doesn't reply, I don't think it means that the dog doesn't have a mind. I think it means the dog can't talk. You need a different kind of test. So a better a kind of test would be something like if I take a pin and I prick the dog, if it experiences pain like I do, then I would withdraw the part of my body that's being pricked.

7:40Skip to 7 minutes and 40 secondsSo my prediction is if I prick a dog, if it has a mind, it will withdraw its paw where I've pricked it. And, as you all know, if you do that, your hypothesis is confirmed. So you may provisionally assume that dogs have states of mind like pain like you do, and you therefore hold provisionally to your inference that dogs, like us, have minds. If you do that to ELIZA, prick her computer, she doesn't withdraw a blooming thing. And so you know she's behaving in a completely different way from you, and so you're probably reasonably right in your inference that in her case the body that you're seeing, that computer, doesn't have a mind.

8:25Skip to 8 minutes and 25 secondsI know I'm putting it sort of semi-comically, but really this is how we proceed. So in a more serious way, what we do is we look at different bodies and we do these sorts of experiments on them, starting always from our own experience. We know in my case if you do this to my body I have this mental state and that is the behavioural outcome. And then you can study the body to see what exactly is it that's linking A to B. So in the case of the pin prick, you can see what about the pin prick, physiologically and anatomically, what is it that causes pain or the lack of it?

9:02Skip to 9 minutes and 2 secondsAnd we've done this sort of thing-- I'm using pain as an example-- we've done this sort of thing with everything to do with the mind. And we find when we do this that the nervous system is the important part of the body. Bodies that have nervous systems behave in the way that we would predict if they have minds. And more particularly, the core of the nervous system, the brain, the central organ of the nervous system-- this seems to be where all the action is. So not all bodies are equal. Not all parts of the body are equal. There seem to be certain bodily correlates of mental experience and other bodily correlates where there's no mental experience.

9:46Skip to 9 minutes and 46 secondsThis is how we go about making this decision that I'm talking to you about, the subjective criterion for determining whether or not something has a mind. It all leads us to the brain. We're led, therefore, to the conclusion that this is where the subjective aspect of the body becomes a mind. That's a big statement, and it's going to need a lot of explaining. And I'm going to start doing that next week. Thanks.

Empathising with other minds

If to know a mind requires that you are that mind, how can you know for certain whether other minds exist? This is a problem in philosophy known as the problem of other minds, and philosophers have rendered this problem insoluble.

But in science, and in everyday life, we don’t usually require absolute certainty, and are happy to rely on provisional truth. We formulate hypotheses, test them, and as long as we cannot falsify these hypotheses, we accept them to be true. In testing whether something has subjectivity or not, we use a systematic common sense approach which comes rather naturally to us. The technical term for this approach is called empathy.